Conventionally, delaminatable containers are known that inhibit entrance of air inside the container by an inner layer delaminated from an outer layer and shrunk with a decrease in the contents (e.g., PTLs 1 and 2). Such delaminatable container is provided with an inner bag composed of the inner layer and an outer shell composed of the outer layer.
A container body of such delaminatable container is generally manufactured by blow molding using a cylindrical laminated parison. The container body has a bottom equipped with a sealing portion when an end of the laminated parison is welded. Since the sealing portion is not resistant to impact, it is provided to protrude from a bottom surface of the container to increase the strength. In PTL 1, to increase the strength of the sealing portion even more, welded layers in the sealing portion are welded to be engaged with each other by a plurality of penetration portions.